This invention relates to a method and apparatus for deep fillet rolling the undercut radii of crankshaft bearings, and more particularly, for deep fillet rolling the undercut radii of crankshaft bearings on a production scale basis.
This invention relates to deep fillet rolling of bearings of crankshafts, which is usually accomplished with a pair of opposed lever arms, each holding a rolling tool at a first end and connected to a hydraulic cylinder or the like at the other end. The cylinder is actuated to spread the other ends to pivot the first ends of the lever arms to apply a predetermined amount of force through the rollers to the crankshaft fillets. Crankshafts have both main bearings located along the central longitudinal axis and pin bearings, at which will be attached the piston rods at various angularly-spaced and radially-spaced positions relative to the central longitudinal and rotational axis of the crankshaft. The crankshaft is rotated during the fillet rolling and the levers and rollers oscillate during the rolling of the pins. The space between adjacent sets of adjacent rolling lever arms for the pins and mains is quite small for many crankshafts, particularly for engines having four, six or eight cylinders and used in the automotive industry.
It is difficult to roll simultaneously all of the pins and mains because of the lack of space between directly-adjacent bearings to accommodate two adjacent, rolling lever arm assemblies. In order to overcome this lack of spacing, adjacent transfer stations have been provided on a crankshaft machining transfer line in which one-half of the bearings, e.g., the odd-numbered bearings, are rolled by a set of lever rolling assemblies spaced from each other; then the crankshaft is shifted to a second transfer station at which the even-numbered bearings are rolled by a second set of lever assemblies that are spaced appropriately because of the absence of the odd numbered-rolling assemblies at this second station. A similar approach has been done in a single machine, where a set of rolling lever assemblies first does one set of pin bearings, e.g., the odd set of pin bearings; and then the pin rolling lever assemblies are shifted axially of the crankshaft and brought into rolling contact with the even-numbered pin bearings. Thus, one set of pin rolling assemblies may be used and spaced instead of using two closely adjacent sets of pin rolling assemblies. In this machine, the main bearing rolling assemblies are stationary, and do not translate in the manner of the pin rolling assemblies.
In the automotive industry, as well as other industries, it is often desired to change the engine displacement; and as a result, the throws on the crankshafts may be changed. Also, it is often desired to be able to perform deep fillet rolling of crankshafts for four, six or eight cylinder engines with the same apparatus. Moreover, it may be desired to use the same fillet rolling apparatus to roll V-block crankshafts or in-line crankshafts. This flexibility to machine various crankshafts is difficult to achieve for a number of reasons. By way of example, an apparatus set up with four stationary rolling tool assemblies for rolling main bearings separating three translatable rolling tool assemblies for rolling respective pairs of pins would be very capable of deep fillet rolling a V-6 cylinder crankshaft having four main bearings separating three respective pairs of pins. But, the same apparatus cannot roll an in-line 6 cylinder crankshaft having seven main bearings separating six pins or a V-8 cylinder crankshaft having five main bearings separating four respective pairs of pins. The apparatus would be ineffective for two reasons. First, there are not enough stationary rolling tool assemblies to roll the 7 main bearings of the in-line 6 cylinder crankshaft or the 5 main bearing of the V-8 cylinder crankshaft. Second, the three translatable rolling tool assemblies are incapable of translating to roll three of the pins on the in-line 6 cylinder crankshaft and two of the pins on the V-8 cylinder crankshaft. Thus, there is a need for a new and more flexible deep fillet rolling method and apparatus that is capable of machining crankshafts designed for a variety of engines.